Number 20 Van Persie brought for Manchester United 20th championship title with three goals expected victory in the Premier League.

Robin van Persie’s signing has been recognised by Roberto Mancini and just about everyone else as the main reason Manchester United are champions for the 20th time.

And last night Van Persie made it his personal crusade to ensure there were no more hiccups and United could start the party.

A magnificent first-half hat-trick gave United the win they needed to put themselves beyond the reach of Mancini’s Manchester City with four games remaining.

No wonder he got a huge bear hug from manager Sir Alex Ferguson as the United squad completed a lap of honour.

Van Persie – who is the only United player to have featured in every league game so far this season – will no doubt reflect that his decision-making last summer proved as sharp as his goal scoring has been in the past two seasons.

First, his controversial decision to leave Arsenal proved right with the Gunners going trophyless for an eighth successive season.

The harder choice to reject Manchester City’s overtures to join United has also proved spot on.

At 29, time was beginning to run out in his quest for a league title but now he has one.

Last night’s result was never in doubt from the moment Van Persie struck his first after just 80 seconds. He added his second – a thunderous volley – in the 13th minute and his third after 33 minutes.

His second hat-trick for United carried an added bonus for the Dutchman.

He has leapfrogged the disgraced Luis Suarez in the race for the Golden Boot. He now has 24 league goals to Suarez’s 23.

But with the Liverpool striker likely to be banned for the rest of the season, he looks set to land the Premier League’s top-gun prize for the second year running. As well as his goals, he has also contributed 13 assists and is in the running for both the PFA and football writers’ player-of-the-year awards.

None of those individual prizes will mean as much to him as his first league winner’s medal.

Aston Villa came in the hope of spoiling the party but never stood a chance after Van Persie had set United on their way.

They never threw in the towel and can take some consolation from preventing United from running up the cricket score they had threatened in the first half. But the result leaves them even deeper in trouble. They are three points ahead of Wigan, having played a game more. And it is looking increasingly likely the fate of the two clubs will be decided when they meet on the final day at the DW Stadium.

It was 16 years ago virtually to the day since Paul Lambert was in the Borussia Dortmund team that knocked United out of the Champions League semi-finals with a 1-0 win at Old Trafford.

But Villa’s dismal record against United – one win in 34 Premier League meetings since 1995 – would not have given him much encouragement of a repeat. And he must have feared the worst after 80 seconds when Van Persie’s tap-in finished off a move started by Wayne Rooney and also involving Antonio Valencia, Rafael and Ryan Giggs.

Replays showed Valencia was offside from Rooney’s initial pass but in the great scheme of things it did not matter. United clearly wanted the game and the title wrapped up as quickly as possible. Van Persie volleyed inches over the bar, Shinji Kagawa was denied by a last-gasp tackle from Ron Vlaar and Rafael struck the post with a long-range shot.

Villa should have drawn level from their first serious venture into United’s half after 11 minutes when Christian Benteke lifted his shot over the bar with only David de Gea to beat.

Manchester United made them pay for their impudence a minute later when they added a quite magnificent goal – both in its creation and finish.

Rooney lofted a perfect 50-yard pass over the defence and Van Persie, pulling away from Vlaar, watched the ball come down over his shoulder before dispatching a left-foot volley past a startled Brad Guzan from the edge of the area.

It was almost identical to a goal he scored for Arsenal last season.

The hat-trick goal came from a another superb move. Rooney, Kagawa and Giggs were involved with Van Persie sidestepping Villa goalkeeper Guzan and then lifting his shot over four defenders on the line.

The second half was something of an anti-climax. Villa improved significantly and Benteke forced a save out of De Gea while Rooney and Kagawa missed chances to increase Manchester United’s lead.

At the final whistle, Van Persie lifted his arms and his eyes to the sky as Old Trafford went into party mode. They may have won 13 Premier League titles but this is only the third time they have done so while playing in front of their own fans.

Suggestions this is not a vintage United team look invalid when they are on course for records in terms of points, wins and title-winning margin.